first forays into stress analysis

[Anonymous]

Hi all,

Now that I'm virtually at the end of the CAD part of this project, I would like to see how far I can go with some FEA. I'll be aided through this process by a mathematician who has done stress analysis before, and a physicist who will put forces together for the frame. I just need to understand the program a bit more.

The first issue I have come across you can see in the attached image. It appears the analysis is faltering on three of the 3 of the 10 bearings. The error reports 'no additional information is available. Internal error in the mesher'. Is this going to affect the analysis? Is there something I can do to resolve this?

Cheers,

OLC

[TheCADWhisperer]

Are all of the bearing the same?

Can you attach BS 290 SKF here?

You should have expanded the Material, Constraints, Loads and Contacts browser nodes for your screen capture.

or

better yet 

attach your assembly here.

[Anonymous]

Ok, a pack and go file is located here:

https://drive.google.com/drive/folders/0B--fBxgwaFykMWszTjFyOXUtV3M?usp=sharing

Three bearings report that the mesh cannot be made, and no matter what force I put into the model, it doesn't seem to show any stressed areas, only displaced areas. Any instructions on how to set up the model for analysis would be greatly appreciated. I'm experimenting in using Drive to share the files so if there is an issue, let me know.

Cheers,

OLC

[TheCADWhisperer]

I don't go to third party sites.

[Anonymous]

That's a shame, but understandable. I'm quite protective over my online footprint and try to keep the number of services I sign up for to a minimum.

From the folder tree which runs horizontally across the top of the webpage, you find the folder 'zipped', with a down arrow and the option to download the zipped file - if anyone would care to have a look and tell me how to make better first moves in FEA I'd be very appreciative.

Cheers

[Anonymous]

Righto,

A little follow up on this. I have made some progress on stress analysis; it was a simple issue - there was a warning message on a loft feature. Once corrected, it has started to run stress analysis. I'm currently running one .IPT at a time first of all rather than build the entire model and run stress analysis in the .IAM

However, I had the first stress analysis results and made an adjustment to the .IPT, When running the second analysis, two bodies separated. I tried to resolve this by combining all bodies, reducing 16 to one. Now when running the stress analysis I get a 'failed sanity check' report which interrupts the mesh construction. I've ctrl+F7 the issue and it hasn't indicated anything wrong.

Any guidance on where to go next to continue exploring the part?

Cheers,

OLC

Part here

ps - how do I add a signature to posts?? Can't find it anywhere in the profile options

[blair · Accepted solution]

The seals are only there to stop any dirt from entering the bearing, so they are irrelevant to the analysis and will only slow it down. Suppress them for the analysis.

Due to the gap between the bodies they will separate unless you set the "Tolerance" in the Contacts when you create a New Study. 

[Anonymous]

Excellent, thanks for looking. I'll investigate the bearings. I'd also come to the same conclusion about the contact between the bodies as yourself, it's good to have had some confirmation that I'm on the right track! It took me a long time to figure out what the problem might be.

Cheers,

OLC

[swalton]

Are you actually interested in the stress results in the bearing races, balls or seals? 

If not, I would abstract them with a solid chunk of steel for the FEA. 

You might be able to use a manual contact between the shaft and the bearing housing.  Make a "Split" surface on the shaft to represent the bearing inner ring and a similar one on the housing to represent the bearing outer ring.  Make a bounded constraint to transfer the loads between the two "Split" surfaces.

See:

Split Face

http://help.autodesk.com/view/INVNTOR/2014/ENU/?guid=GUID-FA9DBC45-7038-4BA8-AB36-FB9C0AEC583C

Manual Contacts

http://help.autodesk.com/view/INVNTOR/2014/ENU/?guid=GUID-4CAFC652-873B-4709-B107-D39A399FCE8D

[Anonymous]

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@Anonymous wrote:

Suppress them for the analysis.

---

I've begun to look into this, and it seems that suppressing the whole bearing doesn't stop the mesh error, and the bearing that is currently in doesn't have a seal. Should supressing the body remove it from the mesh view? It's the one thing prohibiting a successful .iam stress analysis now. I'd rather remove the bearing from the calculations than delete and replace it with a substitute body as suggested. Call that plan b.

Cheers

OLC